diff --git a/packages/storage/src/models.ts b/packages/storage/src/models.ts
new file mode 100644
index 0000000..eb2c3d5
--- /dev/null
+++ b/packages/storage/src/models.ts
@@ -0,0 +1,120 @@
+/**
+ * TypeScript models for GlowTrack data structures
+ * 
+ * Based on the data model specification for mood and habit tracking
+ * with wellbeing grid visualization.
+ */
+
+/**
+ * Color blind accessibility modes supported by the application
+ */
+export type ColorBlindMode = 'none' | 'protanopia' | 'deuteranopia' | 'tritanopia';
+
+/**
+ * Type of habit entry - positive contributes to wellbeing, negative detracts
+ */
+export type HabitType = 'positive' | 'negative';
+
+/**
+ * Settings for PNG export functionality
+ */
+export interface ExportSettings {
+  /** Scale factor for PNG export (1.0 = screen resolution) */
+  pngScale: number;
+  /** Whether to include legend in exported PNG */
+  includeLegend: boolean;
+}
+
+/**
+ * Configuration settings for the wellbeing grid
+ */
+export interface GridSettings {
+  /** Start date for the grid view (ISO date YYYY-MM-DD) */
+  startDate: string;
+  /** End date for the grid view (ISO date YYYY-MM-DD) */
+  endDate: string;
+  /** Theme palette identifier */
+  theme: string;
+  /** Color blind accessibility mode */
+  colorBlindMode: ColorBlindMode;
+  /** Export configuration */
+  export: ExportSettings;
+}
+
+/**
+ * Mood state for a specific day
+ */
+export interface Mood {
+  /** Hue value (0-360 degrees) */
+  hue: number;
+  /** Intensity level (0-1) */
+  intensity: number;
+  /** Optional note about the mood */
+  note?: string;
+}
+
+/**
+ * Definition of a habit that can be tracked
+ */
+export interface HabitDefinition {
+  /** Unique identifier for the habit */
+  id: string;
+  /** Type of habit (positive or negative) */
+  type: HabitType;
+  /** Display label for the habit */
+  label: string;
+  /** Optional icon identifier for UI glyphs */
+  icon?: string;
+  /** Default weight for new entries of this habit */
+  defaultWeight: number;
+  /** Whether this habit is archived (no longer actively tracked) */
+  archived: boolean;
+}
+
+/**
+ * A single habit entry for a specific day
+ */
+export interface HabitEntry {
+  /** Unique identifier for this entry */
+  id: string;
+  /** Type of habit entry */
+  type: HabitType;
+  /** Reference to the habit definition */
+  habitId: string;
+  /** Display label (may differ from habit definition) */
+  label: string;
+  /** Weight of this entry (always positive, type determines sign for net score) */
+  weight: number;
+  /** When this entry was created */
+  timestamp: string;
+}
+
+/**
+ * Data for a single day tile in the wellbeing grid
+ */
+export interface DayTile {
+  /** Date for this tile (ISO date YYYY-MM-DD) */
+  date: string;
+  /** Mood state for this day */
+  mood: Mood;
+  /** Habit entries for this day */
+  entries: HabitEntry[];
+  /** Derived net score: sum(positive weights) - sum(negative weights) */
+  netScore: number;
+}
+
+/**
+ * Complete wellbeing grid data structure
+ */
+export interface WellbeingGrid {
+  /** Stable unique identifier for this grid */
+  id: string;
+  /** When this grid was created (ISO datetime) */
+  createdAt: string;
+  /** When this grid was last updated (ISO datetime) */
+  updatedAt: string;
+  /** Grid configuration settings */
+  settings: GridSettings;
+  /** Day tiles that make up the grid */
+  days: DayTile[];
+}
diff --git a/specs/001-glowtrack-a-mood/tasks.md b/specs/001-glowtrack-a-mood/tasks.md
index 2bd8ccf..c776ac9 100644
--- a/specs/001-glowtrack-a-mood/tasks.md
+++ b/specs/001-glowtrack-a-mood/tasks.md
@@ -111,7 +111,7 @@ Integration scenarios from quickstart.md → e2e smoke tests [P]
 ## Phase 3.3: Core Implementation (only after tests are failing)
 From data-model.md → model creation tasks [P]
 
-- [ ] T016 [P] Define TypeScript models
+- [X] T016 [P] Define TypeScript models
   - Create /home/jawz/Development/Projects/GlowTrack/packages/storage/src/models.ts
   - Export interfaces: WellbeingGrid, GridSettings, ExportSettings, DayTile, Mood, HabitEntry, HabitDefinition
   - Dependencies: T009-T015 (tests exist), T003